Ophthalmic lens with optical sectors

ABSTRACT

The invention relates to an ophthalmic lens comprising a main lens part, a recessed part, an optical center, and an optical axis through said optical center, said main lens part having at least one boundary with said recessed part, said main lens part having an optical power of between about −20 to about +35 dioptre, said recessed part positioned at a distance of less than 2 mm from said optical center and comprising a near part having a relative dioptre of about +1.0 to about +5.0 with respect to the optical power of said main lens part, said boundary or boundaries of said recessed lens part with said main lens part form a blending part or blending parts, are shaped to refract light away from said optical axis, and have a curvature resulting in a loss of light, within a circle with a diameter of 4 mm around said optical center, of less than about 15%.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of International Application No.PCT/NL2010/050078 filed Feb. 17, 2010, claiming priority based on NLPatent Application No. 2002540 filed Feb. 17, 2009 and U.S. ProvisionalPatent Application No. 61/153,044 filed Feb. 17, 2009, the contents ofall of which are incorporated herein by reference in their entirety.

BACKGROUND

The present invention relates to an ophthalmic lens comprising a mainlens part and a recessed part.

One particular type of ophthalmic lenses of that type is an MultifocalIntra Ocular Lens (MIOL). It usually comprises a lens part with acentre, which lens part is provided on the periphery with supportingparts (haptics). Lenses of this type are generally known in the state ofthe art. These are used for replacement of the eye lens after cataractoperations, for example many attempts are made to provide MIOL withconcentric annular optical zones for reading distance and orintermediate vision. In a “simultaneous vision multifocal”, therelationship between the distance zone and the near zone is quitecritical. In order for that type of lens to function properly, it mustpermit approximately equal amounts of light into the eye through boththe near zone and the distance zone. This is required so that vision isnot biased toward either vision correction. Obviously, because of thegreat variation in light levels in daily life, which accordingly changethe diameter of the pupil, a compromise must be reached upon whenselecting the size of each zone. This problem, also refers to as “pupildependency”, is further complicated as the difference in pupil sizevaries substantially from patient to patient. Examples of these types oflenses may be seen in U.S. Pat. Nos. 4,636,049; 4,418,991; 4,210,391;4,162,172; and 3,726,587, and in patent application US 2006/0212117,EP0590025B1, U.S. Pat. No. 6,126,286. Another problem of those annularconcentric designed MIOL are the ghost images and blur due to the lightdirected to the macula at the annular zone transitions. Another bigdrawback of current MIOL is the loss of contrast sensitivity. Contrastsensitivity determines the lowest contrast level which can be detectedby a patient for a given size target. Normally a range of target sizesare used. In this way contrast sensitivity is unlike acuity. Contrastsensitivity measures two variables, size and contrast, while acuitymeasures only size. Contrast sensitivity is very similar to auditorytesting, which determines a patient's ability to detect the lowest levelof loudness of various sound frequencies. The patient is asked todepress a button when the tone is just barely audible and release thebutton when the tone can no longer be heard. This procedure is used totest auditory sensitivity to a range of sound frequencies. If auditorytesting were evaluated in a similar way to visual acuity, all the soundfrequencies would be tested at one high level of loudness.

The problem of pupil dependency of simultaneous vision multifocalperformance is claimed to be diminished by a further embodiment ofsimultaneous vision multifocals that operates under the principles ofdiffraction. Examples of these types of lenses were presented in U.S.Pat. Nos. 4,641,934 and 4,642,112. Due to the nature of diffractiveoptics, at least 20% of the incoming light will be lost and patientssuffer from halos and glare.

To solve this pupil independency several attempts have been made, suchas disclosed in U.S. Pat. No. 4,923,296 which describes a lens dividedinto a series of substantially discrete near and distant vision zones.Not clear from this disclosure is how these vision zones could be madeand or joined together. WO 92/06400 describes a aspheric ophthalmiclens. The surface zones are defined three dimensionally forming ajunctionless, continuous and smooth surface in conjunction with oneanother. It will be clear to a person skilled in the art that such alens will suffer a large decrease of optical quality. U.S. Pat. No.4,921,496 describes a rotation symmetric, radially segmented IOL. ThatIOL has no junctions at the surface, since the materials for eachsegment should have different refractive indices to create the differentpowers.

Another lens with a distance part and a near part is described inEP0858613(B1) and U.S. Pat. No. 6,409,339(B1) by Procornea Holding B.V.from the current inventor, and which are incorporated by reference as iffully set forth. These documents disclose contact lenses, but also referto IOL's. A lens of this type differs from other lenses in that thereading part is located within the (imaginary) boundary of the distancepart. That is to say the reading part is on or within the imaginaryradius of the outer boundary of the distance part (Rv). If a readingpart is used this is preferably made as a sector which extends from thecentre of the lens. This lens proved to have many possibilities. Thereis, however, room for further improvement.

It has been found after extensive clinical testing that for a MIOL asdisclosed in U.S. Pat. No. 6,409,339(B1), the transition profile used tobridge the step height between the sector boundaries is not optimal.This results in reduction of the usable optical area and significantloss of light energy and contrast sensitivity. The optical configurationas disclosed herein provides a distinct bifocal image whereas amultifocal image is necessary to reduce halo's with big pupil size andat the same time have a clear vision with high contrast at near andintermediate distance. EP0858613(B1) and U.S. Pat. No. 6,409,339(B1) inparticular discloses that the transitions should be smooth and have asigmoid or sine shape curve to bridge the step height difference betweenboth optical parts. U.S. Pat. No. 6,871,953, to Mandell, publishedSeptember 2003, surprisingly discloses the same use of sigmoid curvetypes to bridge the step height resulting in exactly the same lensconfiguration as described in EP0858613 (B1). The purpose of the sigmoidcurves in both applications when relating to contact lenses is to makethe transitions between the optical parts as smooth as possible toreduce friction of the eyelid. A drawback of the wide transitionsdescribed therein is that it also creates a high loss of light energyand was found to reduce contrast sensitivity. U.S. Pat. No. 6,871,953discloses to make the transitions wider to create even smoothertransitions. Due to the alternating principle of a contact lens, thecontact lens nowadays moves up on the eye when line of sight is downgaze. The loss of light at the transitions under these alternatingconditions for contact lenses is not determined. The opposite, however,is true for a MIOL. Such a lens is fixed in the eye. The optical usablearea of the semi-meridian sectors will be reduced, which leads to lesslight energy being directed to the macula. This results in poor opticalperformance either for distance or near vision. Furthermore it has beenfound that due to the fact that the pupil size varies under differentlight conditions, unwanted halo effects may occur with big pupil size.Therefore it would be beneficial to have a apodized power profile in thereading part to reduce this phenomenon and introduce multifocallity atsame moment.

U.S. Pat. No. 7,004,585 discloses a multifocal contact lens having ablended design for a segmented optical zone. The contact lens shouldmove on the eye easily in order to make the lower reading zoneavailable. Furthermore, a transition or blend zone should be designed toavoid blur and ghost images. To that end, the blend zone should have asmooth transition to improve wearers comfort. Furthermore, the blendzone should include a curvature magnitude to refract light away from themacular region of the eye. The various optical zones should influenceeach other as little as possible. In this document, patentee seems tohave identified that problem. The solution of making the blend zone assmooth as possible and providing a reading zone in a particular way,however, seems complex. The ophthalmic lens design can be furtherimproved, however. In particular for IOL devices, there is room forfurther improvement.

In U.S. Pat. No. 7,237,894, a ophthalmic lens was designed with a radialcentre below the centre of the optical zone. In that way, however, it isdifficult to avoid an image shift.

SUMMARY OF THE INVENTION

At least some of the disadvantages of the prior art illustrated aboveare overcome by the present invention.

To that end, the invention provides an ophthalmic lens comprising a mainlens part having a surface, a recessed part having a surface which isrecessed with respect to said surface of said main lens part, an opticalcentre, and an optical axis through said optical centre, said main lenspart having at least one boundary with said recessed part, said mainlens part having an optical power of between about −20 to about +35dioptre, said recessed part positioned at a distance of less than 2 mmfrom said optical centre and comprising a near part having a relativedioptre of about +1.0 to about +5.0 with respect to the optical power ofsaid main lens part, said boundary or boundaries of said recessed lenspart with said main lens part form a blending part or blending parts,are shaped to refract light away from said optical axis and have acurvature resulting in a loss of light, within a circle with a diameterof 4 mm around said optical centre, of less than about 15%, said loss oflight defined as the fraction of the amount of in-focus light from theIOL compared to the amount of in-focus light from an identical IOLwithout said recessed part.

This ophthalmic lens allows various optical parts to be integrated inone single lens in such a way that they influence one another as littleas possible. For instance, it allows an ophthalmic lens with a readingpart is such a way that distance vision, intermediate vision and nearvision influence each other little to not. In fact, it was found that wewere able to significantly increase contrast sensitivity of ophthalmiclenses. In the past a lens would be designed to cause as littledisturbance as possible. In the current invention, it was found thatsharp transitions can be allowed, as long as they cause light to berefracted away from the optical axis. In fact, as long as these sharptransitions cause the lens to refract less than 15% of the light wayfrom the optical axis, this would result in for instance an IOL whichprovides improved contrast sensitivity and vision. This loss of light isin fact defined for a pupil diameter of 4 mm.

In this respect, light is defined as light in the visual wavelengthrange. Usually this is between about 400-700 nm.

The amount of in-focus light is the sum of focussed light in all themain focal planes of the IOL. Thus, if for instance the central part hasrelative dioptre 0, and the recessed part has a relative dioptre withrespect to the main lens part, the lens will usually have two focalplanes, one for the main lens part and one for the recessed part. If theoptical area of the recessed part is 30% of the entire lens area and thearea of the main lens part is 70%, and there is no further loss, then30% of the focussed light will be available in the focal plane of therecessed part and 70% of the focussed light will be available in thefocal plane of the main lens part.

In an embodiment, the lens comprises at least one recessed,semi-meridian optical sector which is radially and/or angularlysubdivided into subzones. It thus may comprise an inner sector, anintermediate sector, and an outer sector, located within the (imaginary)boundary of the lens part. The inner sector has a first optical power,the intermediate sector which is adjacent to the inner sector has asecond optical power. The outer sector adjacent to the intermediatesector has a third optical power. The step height between the boundariesof the semi-meridian sectors are joined by means of an optimisedtransition profile to maximize light energy directed to the macula andto reduce blur and halo's at bigger pupil sizes. The ophthalmic lenssemi-meridian sectors can have a continuous power profile.Alternatively, the optical sub circle sectors are blended together.Combinations thereof are also possible. The subdivided sector(s) willprovide a clear vision at reading and intermediate distances, whereasthe distance vision and contrast sensitivity remain comparable with anmonofocal ophthalmic lens.

The present invention may also be configured to provide lenses whichperform well in eyes with varying corneal aberrations (e.g., differentasphericalities), including spherical aberration, over a range ofdecentralization, i.e. deviation between the optical axis or centre ofthe lens and the optical axis of the eye. This means that positioning ofthe IOL becomes less critical.

In an embodiment, the ophthalmic lenses of the invention may comprisemore than three subdivided semi-meridian or semi-meridian sector zones.

In a further embodiment of the invention the opposite surface of thelens may comprise an aspheric surface such that the residual sphericalaberration will be reduced to about zero. For instance such as describedin, but not limited to EP1850793, 1857077 or US2006279697 incorporatedherein by reference.

In a further embodiment of the invention the semi-meridian recessedrefractive reading part can comprise boundaries at all sides, and mayeven comprises an additional diffractive optical element (DOE)structure, for instance such as described in, but not limited to,EP0888564B1 or EP1194797B1, incorporated herein by reference.

Another object of the invention is to provide a method and optimizedcurves to optimise and improve the steepness of the transition profileto bridge height differences between parts of the lens. These blendingparts improved the transition between various parts. Using theseblending parts will reduce loss of light energy and maximizes the usableoptical area(s) significantly. The step height differences at forinstance semi-meridian boundaries may be bridged by methods using acosine trajectory or sigmoid function. In an embodiment, however,optimised transition function are proposed. These derived transitionfunctions consistent with the outcome of the optimised profile functionare consistent with the embodiments of the invention.

The dimension and/or optical power ratio between various parts, forinstance a semi-meridian subdivided reading part and a distance part,may mutually vary. If two lenses are used, for both eyes of the patient,one lens can be configured for the dominant eye and the other lens forthe non-dominant eye. That is to say, the lens for one eye has adifferent configuration for the reading part or distance part than thelens for the other eye.

It is also known that there is a functional dependence between pupilsize and luminance. For example, such data was reported in Glen Myers,Shirin Berez, William Krenz and Lawrence Stark, Am. J. Physiol. Regul.Integr. Comp. Physiol, 258: 813-819 (1990). Pupil size is a function ofthe weighted average of the luminances (popularly called brightness)within the field of view. Pupil size is influenced much more by the partof the retina associated with central, or foveal, vision than by theouter areas of the retina.

The following listing presents some levels of field brightness andassociated “typical” conditions

Field brightness (cd/m2) Condition 30 Subdued indoor lighting 60 Lessthan typical office light; sometimes recommended for display-onlyworkplaces 120 Typical office 240 Bright indoor office 480 Very bright;precision indoor tasks 960 Usual outdoors 1920 Bright afternoon

A customized recessed semi-meridian lens could be designed by usingcertain field brightness conditions to calculate the optimal centralpart and or reading part in relation to the specific pupil diameter.

Apart from the corrective distance sector and semi-meridian subdividednear sector described above, further corrections can be made in the lenssectors to optimize or correct particular optical abnormalities. Itshould be understood that a further structure, which makes it possibleto correct all kinds of optical abnormalities, such as but not limitedto astigmatism and spherical aberration, can be arranged at the anterioror posterior side of the current lens.

The recessed part, for instance formed as a semi-meridian readingsector, is positioned in the eye in an embodiment at the lower part orbottom (inferior) of the lens because this corresponds to the naturalinclination of people to look down when reading. However, thepositioning of the semi-meridian reading sector in the eye is notcritical and can be positioned Superior, Inferior, Nasal or Temporal.Distant and near sectors can even be disposed in opposite arrangementfor the two eyes of one person.

The ophthalmic lens or mould described herein can be made in any wayknown in the art. For an intraocular lens, for instance, it is inaddition possible to make the lens part and the haptic separately and toconnect them together later. However, it is also possible to make themas one entity. According to an embodiment, these parts are made as oneentity by (injection) moulding. A subsequent processing for producingthe proper lens parts can be turning. As described in U.S. Pat. No.6,409,339B1, during such a turning operation a tool bit can be movedevery revolution towards and away from the lens in the directionparallel to the rotational axis. This makes it possible to produce thelens part by turning. It is also possible according to an embodiment toperform the turning so finely that a subsequent polishing operation canbe omitted. The material of the lens can be any desired material.

The novel ophthalmic lens optic configuration for example can also beused for contact lenses and for pseudophakic intra-ocular lens patientsas a so called “add on lens”. This is an extra or additional lens whichcan be placed in front of a existing natural lens or in front of aartificial intra ocular lens to correct refraction errors and or torestore reading capabilities. The add-On lens could be placed in thebag, the sulcus, as cornea inlay or as a anterior chamber lens.

With modern lens power mapping apparatus, such as the High resolutionHartmann Shack system “SHSInspect Ophthalmic”, commercial available fromOptocraft Germany, it is possible to determine the local refractivepowers and a wide range of relevant surface variations. Suchmeasurements can therefore identify a lens made in accordance with thepresent invention very easy.

In an embodiment, the curvature results in a loss of light, within acircle with a diameter of 4 mm around said optical centre, of betweenabout 2% to about 15%. In fact, usually the recessed part extendsfurther than 4 mm in radial direction. In the calculations of the lossof light, reference is made to the blending parts which are enclosed byor are positions within two meridians or, to be more precise,semi-meridians running from the optical centre to the rim of a lens.

The actual loss of light, or better loss of intensity, can be measuredwith a PMTF system which is commercially available from Lambda-X SA Ruede l'industrie 37 1400 Nivelles Belgium. This instrument is capable ofmeasure the loss of intensity. The procedure for this measurement willbe discussed below in the description of embodiments.

In an embodiment, the main lens part has an optical power of betweenabout −10 to about +30 dioptre.

In an embodiment, the recessed part is positioned at a distance of lessthan 1.5 mm from said optical centre. In this respect, the distance isdefined as the nearest radial distance from the optical centre.

In an embodiment, the near part has a relative dioptre of about +1.50dioptre to about +4.00 dioptre with respect to said main lens part.Thus, it allows use as a reading part, for instance. The optics of thecentral part as well as of the main lens part and of the recessed partcan furthermore be designed to be toric, cylindrical or be designed tocompensate higher order aberrations. These types of lens design are assuch known to a skilled person, and can additionally be applied to thevarious lens parts of the current invention.

In an embodiment, the semi-meridian boundary or boundaries of saidrecessed lens part with said main lens part have a curvature resultingin a loss of light, within a circle with a diameter of 4 mm around saidoptical centre, of below about 10%.This very low loss of light, inparticular in combination with the refraction away from the opticalaxis, already results in a higher contrast sensitivity and good readingability.

In an embodiment, the main lens part has a curvature with substantiallya curvature radius Rv, and the outer limit of the recess, i.e. itssurface, lies on or within the curvature radius Rv.

In an embodiment, the ophthalmic lens further comprises a central partwhich has a relative optical power of −2.0 to +2.0 dioptre with respectto said main lens part. Thus, it may be possible to require a recessedpart to be less deep and thus the blending parts to have less influence.

In an embodiment, the size of said central part is such that it fitswithin a circumscribing circle with a diameter of about 0.2-3.0 mm.Thus, it was found that distance vision would be influenced as little aspossible by the recessed part. In an embodiment, the size of saidcentral part is such that it fits within a circumscribing circle with adiameter of about 0.2-2.0 mm. In an embodiment, said central part issubstantially circular.

In an embodiment of the lens with a central part, the lens comprises afurther blending part between the central part and the recessed part.This blending part usually is concentric or almost concentric withrespect to the optical axis. In an embodiment, the further blending parthas a smooth transition. Alternatively, the slope has a kink. In thisembodiment, the first derivative of the slope is discontinuous. Thus,the curvature radius of the surface has a kink. An advantage of thisembodiment is that the recessed part will be less deep with respect tothe main lens part. Alternatively, the further blending part is closeto, approaches or is a step function. As this further blending part isconcentric, this causes little disturbance in vision.

In an embodiment, the recessed part is bounded by semi meridians runningthough said optical centre, the recessed part thus having the shape of ameridian zone. In fact, the blending parts which blend the main lenspart and the recessed part thus follow meridians as much as possible. Infact, such a blending part will be arranged between two semi meridiansrunning through the optical centre.

In an embodiment comprising said central part, said recessed part is atat least one boundary bounded by said central part.

In an embodiment comprising said central part, said central part has across section of about 0.60-1.20 mm. This allows a recessed part whichinfluences for instance contrast sensitivity as little as possible.

In an embodiment comprising said recessed part shaped as a meridian zonesaid recessed part has an included angle of about 160-200 degrees. Insuch an embodiment, at least two boundaries with the main lens partsubstantially follow meridians. In practice, these boundaries are formedby blending parts. As already stated above, usually such a blendingparts is clamped between two semi meridians. In practice when using anoptimised curve explained below, the blending part will not exactlyfollow a meridian, but will be slightly curved. In an embodiment saidrecessed part has an included angle of about 175-195 degrees.

In an embodiment, the ophthalmic lens has a cross section of about 5.5-7mm. In particular in case of an intraocular lens, or another ocularysupported lens like a contact lens, it will to in such a diameter range.

In an embodiment the main lens part is in the form of a distance lens.

In an embodiment the recessed part forms a reading part.

In an embodiment comprising said central part, said recessed part isbounded by two semi meridians and a line of latitude concentric and at adistance from said central part.

In an embodiment said recessed part comprises at least two sub-zonehaving optical powers which differ.

In an embodiment, these sub-zones are concentric.

In an embodiment optical powers of said sub-zones increase in radialdirection.

In an embodiment optical powers of said sub-zones decrease in radialdirection

In an embodiment the optical power of the recessed part increases inradial direction. Thus, it is possible to provide an intermediate visionpart between the main lens part and, if present, central part, and anear or reading part provided in the recessed part. The blending betweenthese increasing optical power regions or zones should be designedcarefully. It may require compensation of less step height in blendingparts.

In an embodiment said recessed part comprises a diffractive optics part.The diffractive optics may be superposed unto the surface of therecessed part. In general, a diffractive optical superposed part on alens surface is known. In case of a recessed part, however, it may allowthe recessed part to be less deep.

In an embodiment, the recessed part comprises a first, central subzoneand two further subzones circumferentially neighbouring at both sides ofsaid first subzone. In an embodiment thereof, said first subzone has anoptical power larger than the optical power of the further subzones. Inan embodiment, the two further subzones have an optical power largerthan the optical power of said remaining lens part.

In an embodiment meridians bound said recessed part. In fact, twosemi-meridians bound said recessed part, thus defining the recessed partas a sector part or wedge part (like a wedge of pie). If the ophthalmiclens has a central part as defined above, this sector part has a partfrom the forming a sector part having a part of the tip taken away.

In an embodiment, the blending parts are within meridian which enclosean angle of less than 17°, in a particular embodiment less than 15°. Inan embodiment, blending parts can even be designed to be within meridianwhich enclose an angle of less than 5°. This, however, requires a verycareful design of the curves and slopes or derivatives of the curves.

In an embodiment said the slope of the blending parts has an S-curve andhave a steepness with a slope or first derivative at a central range ofthe blending part at 1.6 mm from said optical centre of more than 0.1,in an embodiment more than 0.4 at its steepest part. In an embodimentsaid blending parts have a steepness with a slope or derivative at acentral range of the blending part at 2.8 mm from said optical centre ofmore than 0.2, in an embodiment more than 0.7 at its steepest part.

In an embodiment, at least one of said blending parts, in particular atleast one semi meridian blending part, has an S-shaped curve whichfollows a first parabolic curve running from the main lens part surfacetowards the surface of the recessed part, having an intermediate curvepart connecting to said first parabolic curve, and continuing withfollowing a second parabolic curve ending at the recessed surface.

In an embodiment, said intermediate curve part at its steepest part hasa first derivative of at least 0.05 at 0.4 mm from said optical centre,in an embodiment at least 0.1 at 0.8 mm, in an embodiment at least 0.15at 1.2 mm, in an embodiment at least 0.2 at 1.6 mm, in an embodiment atleast 0.3 at 2.0 mm, in an embodiment at least 0.4 at 2.4 mm, in anembodiment at least 0.5 at 2.8 mm.

The invention further pertains to an add-on intraocular lens to beinserted in the bag, the sulcus, as cornea inlay or an anterior chamberlens, comprising the ophthalmic lens according to any one of thepreceding claims, wherein said main lens part has an optical power ofabout −10 to +5 dioptre.

The invention further relates to an ophthalmic lens comprising a mainlens part having substantially a curvature radius Rv, a substantiallycircular central part having a first optical property and having a crosssection of about 0.2-2.0 mm, and a meridian part comprising a recesswhich is bounded by said substantial circular central part, by twomeridians running through the centre of said circular part, and by alower boundary which is substantially concentric with respect to saidcircular part, said meridian part formed as a recess in said lens, theouter limit of the recess lying on or within the curvature radius Rv,said meridian part comprising a reading part.

The invention further relates to a method for the production of one ofthe ophthalmic lenses described above, comprising a step of turning, inwhich a lens blank is positioned on a rotating machining holder and issubjected to the influence of one or more material-removing devices,characterized in that during the turning step the rotating lens and saidmaterial-removing device are moved to and away from one another in thedirection of the axis of rotation, in order to form at least onerecessed portion in said ophthalmic lens. This production method allowsproduction of lenses having the properties required.

The invention further relates to an ocularly supported multifocalcorrective lens provided with a substantially circular central lensportion, a lower lens portion in a lower lens part neighbouring saidcentral lens portion, and a further lens portion, the lower lens portioncomprises a recess comprising two sides which run from said central lensportion towards the rim of the lens, the outer limit of the lower lensportion lies on or within an imaginary sphere having its origin andradius of curvature coinciding with the radius Rv of said further lensportion, wherein said two sides provide sloping from the further lensportion surface to the recessed surface of the lower lens portion, saidsloping following a first parabolic curve running from the further lensportion surface towards the lower lens portion surface, and continuingwith following a second parabolic curve ending at the recessed surface.

The invention further relates to an ophthalmic lens comprising a mainlens part, a recessed part, an optical centre, and an optical axissubstantially through said optical centre, said main lens part having atleast one boundary with said recessed part, said recessed partpositioned at a distance from said optical centre, boundaries of saidrecessed lens part with said main lens part are formed as blending partswhich are shaped to refract light away from said optical axis, said mainlens part, central part, recessed part and blending parts mutuallypositioned and shaped for providing a Log CS characteristic underphotopic light conditions, usually at about 85 cd/m², within 6 monthspost operative, in a spacial frequency (cpd) between 3-18 which is atleast between the population norm of 11-19 years and 50-75 years.

In an embodiment of this lens, in a spacial frequency (cpd) betweenabout 6 and 18, its Log CS characteristic under photopic lightconditions, within 6 months post operative, usually at about 85 cd/m²,is in the range of normality above the population norm of 20-55 yearsold adults with healthy eyes.

The invention further relates to an intraocular lens comprising a mainlens part, a recessed part positioned at a distance from an opticalcentre, and a central part in said optical centre and which issubstantially circular, has a diameter of about 0.8 to 2.8 mm, and atone side bounding said recessed part, wherein the diameter of saidcentral part is adapted to the pupil diameter of the wearer.

In an embodiment, the diameter of said central part is about 20-40% ofthe pupil diameter of the wearer at office lighting conditions, i.e.200-400 lux. Thus, the IOL can be custom-made.

Various aspects and/or features described in this text may be combined.Features and aspects may also form part of one or more divisionalapplications referring, for instance, to aspects of the productionresulting in methods, specific types of ophthalmic lenses, like the oncementioned in this text, or to specific features like the blending ortransition zones, the recessed part and its features, or the centralpart.

DESCRIPTION OF EMBODIMENTS WITH REFERENCE TO THE DRAWINGS

The invention will be further elucidated referring to embodiments of aMultifocal Sector Ophthalmic Lens, (MSOL) shown in the attacheddrawings, showing in:

FIG. 1 a cross section of a human eye;

FIG. 2 a cross section of a human eye with an IOL;

FIG. 3 a front view of an embodiment of an MSIOL with an optical centralpart and a recessed part;

FIG. 4 a side view of the MSIOL according to FIG. 3;

FIG. 5 a cross sectional view over line IV of the MSIOL according toFIG. 3;

FIG. 6 a detail of the cross section according to FIG. 5;

FIG. 7 a perspective front side view of the MSIOL according to FIG. 3;

FIG. 8 a perspective back side view of the MSIOL according to FIG. 3;

FIG. 9 a front view of another embodiment of an MSIOL with a recessedpart subdivided in three meridianally divided optical sectors and onecentral optical sector;

FIG. 10 a side view of the MSIOL according to FIG. 9;

FIG. 11 a perspective front side view of the MSIOL according to FIG. 9;

FIG. 12 a front view of a further variant of the MSIOL with a recesseddiffractive semi-meridian sector element;

FIG. 13 a side view of the MSIOL according to FIG. 12;

FIG. 14 a cross sectional view over line XIV of the MSIOL according toFIG. 12;

FIG. 15 a detail of the cross section according to FIG. 14;

FIG. 16 a perspective front side view of the MSIOL according to FIG. 12;

FIG. 17 a comparison between a optimised transition trajectory andcosine trajectory of a transition or blend zone or part, illustratingthat in the same time with the optimised profile a larger displacementis possible;

FIG. 18 the sigmoid function without any scaling and translation on theinterval [−10,10];

FIG. 19 the experienced or effective acceleration (second derivative)during the sigmoid transition;

FIG. 20 the reduction of the transition zone width by calculating theneeded transition time and distance according the method described inthis document locally, the transition zone width is zero near thecentre;

FIGS. 21-26 graphs showing the energy distribution in various parts ofseveral embodiments of ophthalmic lenses;

FIGS. 27-29 measured data of ophthalmic lenses;

FIGS. 30-32 graphs of steepness's of blending or transition zones orparts;

FIGS. 33 and 34 test results showing the Log CS against the spatialfrequency;

FIG. 35 showing a surface model of one of the embodiments;

FIG. 36 a schematic setup of measuring instrument PMTF.

DETAILED DESCRIPTION OF EMBODIMENTS

A preferred embodiment of the invention is now described in detail.Referring to the drawings, like numbers indicate like parts throughoutthe views. As used in the description herein and throughout the claims,the following terms take the meanings explicitly associated herein,unless the context clearly dictates otherwise: the meaning of “a,” “an,”and “the” includes plural reference, the meaning of “in” includes “in”and “on.” Unless defined otherwise, all technical and scientific termsused herein have the same meanings as commonly understood by one ofordinary skilled in the art to which this invention belongs. Generally,the nomenclature used herein and the laboratory procedures are wellknown and commonly employed in the art. Conventional methods are usedfor these procedures, such as those provided in the art and variousgeneral references.

It should be understood that the anterior optical sectors are preferablyconcentric with the geometric centre of the posterior surface

A “vertical meridian” refers to an imaginary line running verticallyfrom the top, through the centre, to the bottom of the anterior surfaceof an MSIOL when said MSIOL is maintained at a predetermined orientationinto the eye

A “horizontal meridian” refers to an imaginary line running horizontallyfrom the left side, through the centre, to the right side of theanterior surface of an MSIOL when said MSIOL is maintained at apredetermined orientation into the eye. The horizontal and verticalmeridians are perpendicular to each other.

“Surface patches” refer to combinations of curvatures and lines that arecontinuous in first derivative, preferably in second derivative, fromeach other.

A “outer boundary”, in reference to a zone other than a central opticalzone on the surface of an MSIOL, refers to one of two peripheralboundaries of that zone which is further away from the geometric centreof the anterior surface.

An “inner boundary”, in reference to a zone other than a central opticalzone on the surface of an MSIOL, refers to one of two peripheralboundaries of that zone which is closer to the geometric centre of theanterior surface.

A “semi-meridian” refers to an imaginary line running radially from thegeometric centre of the anterior surface of an MSIOL to the edge of thelens.

The “upper portion of the vertical meridian” refers to one half verticalmeridian that is above the geometric centre of the anterior surface ofan MSIOL, when said lens is maintained at a predetermined orientationinside an eye.

The “lower portion of the vertical meridian” refers to one half verticalmeridian that is below the geometric centre of the anterior surface ofan MSIOL, when said lens is maintained at a predetermined orientationinside an eye.

A “continuous transition”, in reference to two or more sector, meansthat the slope of these sectors are continuous at least in firstderivative, preferably in second derivative.

A “vertical meridian plane” refers to a plane that cuts through theoptical axis of an MSIOL and a vertical meridian on the anterior surfaceof the MSIOL.

As used herein in reference to the sectors or parts of an MSIOL theterms “Baseline Power”, “optical power”, “Add Power” and “Dioptre power”refer to the effective optical or Dioptre power of a sector when thelens is part of an ocular lens system such as for instance a cornea, aMSIOL, a retina and the material surrounding these components. Thisdefinition may include the effects of the divergence or angle of lightrays intersecting the MSIOL surface caused by power of the cornea. Incertain instances, an algorithm for calculating the Dioptre power maybegin with a ray-tracing model of the human eye incorporating asubdivided sector MSIOL. At a particular radial location on the MSIOLsurface Snell's law may be applied to calculate the angle of the lightray following the refraction. The optical path length of the distancebetween a point on the surface and the optical axis (axis of symmetry)may be used to define the local radius of curvature of the local wavefront. Using such an approach, the Dioptre power is equal to thedifference in indices of refraction divide by this local radius ofcurvature.

The present invention aims to improve ophthalmic lenses, and in oneaspect relates to an novel Multifocal Sector Intra Ocular Lens (MSIOL)with at least two semi-meridian optical sectors where at least one ofthe semi-meridian optical sectors is radial or angular subdivided andcould comprise an inner sector, an intermediate sector, and an outersector, located within the (imaginary) boundary of the distance part.The inner sector has a first optical power, the intermediate sectoradjacent to the first optical power has a second optical power. Theouter sector adjacent to the second optical power has a third opticalpower whereas the step height between the boundaries of thesemi-meridian sectors are joint by means of a optimised transitionprofile to maximize light energy directed to the macula and to reduceblur and halo's at bigger pupil size. The ophthalmic lens semi-meridiansectors could have a continuous power profile or the discrete opticalsub circle sectors blend together or combinations thereof. Thesubdivided sector(s) will provide a clear vision at reading andintermediate distances. Whereas the distance vision and contrastsensitivity remain comparable with an mono focal ophthalmic lens withreduced blur and halo's at bigger pupil size. The present invention mayalso be configured to perform well across eyes with different cornealaberrations (e.g., different asphericities), including the sphericalaberration, over a range of decentration.

The ophthalmic lens may be designed to have a nominal optical power fordistance vision, defined as “Baseline Power”, usually of the main lenspart, an “Add power” added on top of the nominal optical power orBaseline power, and intended for the reading vision. Often, also anintermediate optical power is defined suited for the particularenvironment in which it is to be used. In case of an MSIOL, isanticipated that the nominal optical power or baseline power of an MSIOLwill generally within a range of about −20 Dioptre to at least about +35Dioptre. The “Add power” will generally be in a range of about +1Dioptres to at least about +5 Dioptre. Desirably, the nominal opticalpower of the MSIOL is between about 10 Dioptres to at least about 30Dioptre, the “Add power” will be between about +1.50 and +4.00 Dioptre.In certain applications, the nominal optical power of the MSIOL isapproximately +20 Dioptre, and the Add power about +3.00 Dioptre, whichis a typical optical power necessary to replace the natural crystallinelens in a human eye.

In FIG. 1, a schematic view of a human eye 100 with its natural lens 106is shown. The eye has a vitreous body 101 and cornea 102. The eye has ananterior chamber 103, iris 104 and ciliary muscle 105 which hold thelens. The eye has a posterior chamber 107. In FIG. 2, the eye 100 isshown with an intra ocular lens 1 replacing the original lens 106.

In FIG. 3, an embodiment of an intra ocular lens (IOL) 1 is shown whichhas haptics 2 and a lens zone or lens part 3. The lens part 3 is theactual optically active part of the IOL 1. The haptics 2 can have adifferent shape. In this embodiment, lens part 3 has a central part 6which is usually substantially circular. It may deviate a little from anabsolute circle, but in most embodiments it is as round or circular aspossible in the specific further lens design. The lens part 3 furtherhas a meridian part in a recess area. This recess is below the surfaceof the curved surface of the remaining lens part 4 of lens part 3. Inother words, the curved surface of the remaining lens part 4 has aradius of curvature Rv, and the recess of the meridian part lies on orwithin the curvature radius Rv (see FIG. 4). It should be clear thatcurved surface of the lens part can be non-spherical or aspheric. Infact, the curved surface can be as described in for instance U.S. Pat.No. 7,004,585 in columns 6, 7 and 8. In particular the Zernikepolynomials can be used to describe any curved surface of an ophthalmiclens.

In this embodiment, the meridian part is divides into two concentricsub-zones 7 and 8.

The various parts, i.e. the central part 6, inner meridian part 7 Andouter meridian part 8, each have a have an angle of refraction or powerwhich differs from the remaining lens part 4. When the lens part 3 isconsidered as part of a sphere having an axis through the crossing oflines R and S, then the central part 6 can also be defined as bounded bya first line of latitude. In this definition, sub-zone 7 can be definedas bounded by two meridians, the first line of latitude and a secondline of latitude. Following this same definition, sub-zone 8 can bedefined as bounded by the two meridians, the second line of latitude anda third line of latitude. In most embodiments, the meridian part (incartography an area of this shape is also referred to as “longitudinalzone”) is referred to as a “reading part”.

The MSIOL comprises a near part or reading part which is bounded on orwithin the lens zone 3 whereas the transition between those parts isperformed with a cosine function or sigmoid function, but desirablyjoined with the optimized transition function discussed below. Ingeneral terms, these general transitions curves are referred to asS-shaped curves. These transitions have a width and are referred to asblending zone or transition zone.

The near or reading part in an embodiment has an included angle αbetween about 160 and 200 degrees. In a further embodiment, the includedangle is between about 175 and 195 degrees. The reading part canoptically be sub divided into at least two imaginary circle sectors 7and 8, forming a continuous transition surface radial about the opticalaxis or geometric axis. The required shape (and curvature of therecessed surface) of those circle sectors 7, 8 can be calculated usingray tracing to control at least the amount of spherical aberration andfurther to avoid image jumps. The reference lines in the lens part 3 areimaginary and for dimensional reference purpose. They are, however, notvisible in the real product.

The lens part 3 in this embodiment has an outer diameter between about5.5 and about 7 mm. In a preferred embodiment, it is about 5.8-6.2 mm.The central part or inner sector 6 has a optical power at least equal tothe baseline power. Desirably, the optical power of the inner circlesector or central part 6 is between 0% and 100% of the Add power.

The central part 6 in an embodiment has a diameter of between about 0.2mm and 2.0 mm. In an embodiment, the diameter of the central part 6 isbetween about 0.60 and 1.20 mm. In case the central part 6 is notabsolutely round, it is a circumscribing circle having the diameterrange mentioned here.

Circle Sector or central part 6 has a optical power at least equal tothe baseline power. In this embodiment, the recessed part has twoindicated subzones, a first subzone 7 near the central part 6. Thisinner subzone has a latitude radius of between about 1.5 and 2.3 mm. Inan embodiment, it is between about 1.8 and 2.1 mm. The outer subzone 8has an optical power equal or greater than the baseline power. In anembodiment, the optical power is between 0 and 100% of the Add power.Thus, it forms an intermediate between the main lens part or the centralpart, and a near part in outer subzone 8. The latitude radius of outersubzone 8 has a dimension between about 2.2 and 2.7 mm. In anembodiment, it can be between about 2.3 and 2.6 mm. In this embodiment,the main lens part almost continues at part 9. The outer limit radiuswhere the lens main lens part 4 continues can have a latitude radius ofbetween about 2.6 and 2.8 mm. In an alternative embodiment, severalconcentric subzones can be provided in order for the recessed part todisturb or influence the central part for distance vision as little aspossible.

The IOL 1 has two semi meridian blending zones or blending parts 10bounding the recessed part 7, 8. These semi meridians bounding blendingparts 10 have an angle γ. In an embodiment, the angle will be less than35°. In an embodiment, it will be less than 17°. In particular, theangle γ will be less than 5°. Usually, it will be more than about 1°.

The recessed part in this embodiment further has a blending zone 11which is concentric with respect to the optical axis R. Main lens part 4continues in the concentric region indicated with reference number 9.

In FIGS. 9-11, several view of another example of an ophthalmic lens isshown, as an Intra ocular lens. In this embodiment, again the recessedpart is divided into subzones. Here, the two outer subzones 7 areangularly arranged at both sides of a central subzone 8′. The MSIOLcomprises a main lens part 4 with a recessed part with a total includedangle α between 160 and 200 degrees, desirably between 175 and 195degrees. The included angle of the outer subzones 7 is between about 10and 30 degrees. In an embodiment, it is between about 15 and 25 degrees.The included angle β of the central subzone 8′ is between about 80 and120 degrees. In an embodiment, the central subzone 8′ is between 85 and100 degrees.

The total included angle of the subzones 7, 8′ for near and intermediatevision are bounded by the main lens part 4. The transitions or blendzones between the various parts follow a cosine function or sigmoidfunction. In an embodiment, they follow an optimized transition functiondescribed below. Due to this optimized transition profile at least oneof those imaginary transition lines will be curved.

The subzones 7 and 8′ are radial arranged around the geometric axis. Theoptical shape of those circle parts are ray traced to control the amountof spherical aberration and further to avoid image jumps. The referencelines in the lens parts are imaginary and for dimensional referencepurpose only and are not visible in the real product. The lens part hasa outer diameter dimension between 5.5 and 7 mm. In an embodiment, thediameter is about 6 mm. The central part 6 has a optical power at leastequal to the baseline power of the main lens part. The diameter ofcentral part has a diameter of between about 0.2 mm and 2.0 mm. In anembodiment, the diameter is between about 0.40 and 1.20 mm. The recessedpart can have a radial width of between about 1.5 and 2.3 mm. In anembodiment, the width is between about 1.8 and 2.1 mm. In an embodiment,the outer subzones 7 have a optical power of about 30 to 60% of the Addpower, i.e. about 30-60% of the relative dioptre of the central part 8′.

The MSIOL as shown in FIGS. 3-8 may also be used in conjunction withanother optical device such as a Diffractive Optical Element (DOE) 20.In an embodiment shown in FIGS. 12-16, such an embodiment is shown. ThatMSIOL comprises a recessed lens part 7 shaped as a refractivesemi-meridian part having a first optical power. The total includedangle γ of the recessed part can be between about 160-200 degrees. In anembodiment, the enclosed angle is between about 175-195 degrees. Thediffractive optical element 20 is superposed on the surface of therecessed part 7. It is shown in an exaggerated way with larger scaledfeatures. In practice, the features of the diffractive optical element20 can be around about 0.5-2 micron in size. In an embodiment, thediffractive optical element 20 can be provided in the outer radial partof the recessed part 7. Thus, the central part 6 can have the sameoptical power or differ only up to about 1 dioptre with respect to themain lens part 4. The first subzone of the recessed part 7 can differ0.5-2 dioptre with respect to the central part 6.

The refractive reading part as described in FIGS. 3-8 may have anadditional DOE element to correct for chromatic aberration or to furtherimprove the distance and reading performance of the MSIOL. This isdepicted in FIGS. 12-16. The DOE part 20 may be ray traced to controlthe amount of spherical aberration and further to reduce halo's andglare. The lens zone 3 also has a outer diameter of between about 5.5 to7 mm. In an embodiment, it is about 5.8-6.2 mm. The central part 6 has aoptical power at least equal to the baseline optical power of remaininglens part 4. Desirably, the optical power of the inner circle sector 7is between 0% and 100% of the Add power. The embedded semi-meridiancircle sector used as the refractive base for the DOE 20 has a opticalpower 10% and 100% of the Add power. The recessed part has a width (fromthe end of the central zone to blending past 11) between 1.5 and 2.3 mm.In an embodiment, it is between 1.8 and 2.1 mm. The DOE 20 may beconfigured for the baseline power and the intermediate Add power.

In an embodiment, transition zones or blend zones 10 bounding therecessed part of the embodiments described in FIGS. 3-16 can follow acosine function or a sigmoid function. In an embodiment, the transitionzones 10 follow an optimized transition function described below. Thetransition or blending zones 13 and 13′ can also follow such a function.

EXAMPLES

Several lens configurations based on FIGS. 3-8 are presented below, foran IOL. For several pupil diameters, the area covered in mm² by thevarious sectors (zones or regions) are shown. In several graphs, thetheoretically determined, relative light energy based on the areacovered by the various sectors is shown. (Sector Radius Central refersto the radius of the central part). These theoretical examplecalculation were done as if the lens has no radius of curvature, i.e. aflat surface. This method has been chosen to simplify the calculationbecause the curvature of the lens surface will change with the opticalpower. The equations for calculating the surface area of a transitionarea used in the embodiments below are as follows.

$A_{Pupil} = {\frac{\pi}{4}D_{pupil}^{2}}$$A_{Near} = {\frac{\alpha_{near} \cdot \pi}{360 \cdot 4}\left( {D_{pupil}^{2} - D_{dist}^{2}} \right)}$$A_{Dist} = {{\frac{\alpha_{far} \cdot \pi}{360 \cdot 4}\left( {D_{pupil}^{2} - D_{dist}^{2}} \right)} + {\frac{\pi}{4}D_{dist}^{2}}}$$A_{Transition} = {\frac{\alpha_{trans} \cdot \pi}{360 \cdot 4}\left( {D_{pupil}^{2} - D_{dist}^{2}} \right)}$

It was found that these values can also be determined usingmeasurements. To that end, an instrument called PMTF can be used. Thisinstrument is available from Lambda-X SA, Rue de l'industrie 37, 1400Nivelles, BELGIUM. In the measurement procedure, an IOL is placed in anISO model eye. A schematic drawing of the principle of PMFT is shown inFIG. 36, showing a light source 380, a target 381 for providing aspacially defined light area, a collimating lens 382, an aperture 383, aset of lenses L1 and L2, An ISO eye model 384 holding the IOL in acuvette, a microscope 385 on a translation table 386 and a CCD camera387 mounted on said microscope 385. In the measurements used below, theeye model has a 4 mm diameter aperture for simulating the pupil.

The measurement procedure and data handling were as follow. The order ofmeasurements of the IOLs can be reversed. In the measurements, an IOLwith only one optical zone is measured, and the same IOL but with anoptical zone according to the invention is measured using the sameprocedure.

The measurements are performed according to the normal use of the PMFT.In this case, first a reference IOL without recessed part was measured.In the focal plane the light within an image of the aperture wasmeasured by integrating the calibrated intensity on the CCD sensor.Next, an IOL with recessed part was measured. To that end, first thedifferent focal planes of the IOL and the focal plane of the referenceIOL are located. The intensity was measured in the focal planes of theIOLs. Thus, in case of an IOL with a far region (the main lens part) anda near region in the recessed part, the light in two focal planes wasmeasured. From the light measurements on the CCD camera, the light inthe focal planes was added and compared to the light in the focal planeof the reference IOL. The measured values for light loss correspondedvery well with theoretically calculated light loss.

Embodiment 1, FIG. 24

Sector Angle Distance 182 Sector Angle Near 170 Sector Angle Transitions8 each recess 4 degrees transition Sector Radius Central 0.57 Pupildiameter 4.00 4.00 3.50 3.50 3.00 3.00 2.50 2.50 2.00 2.00 1.50 1.501.14 1.14 Area Pupil 12.57 9.62 7.07 4.91 3.14 1.77 1.02 Area nearsector 5.45 43% 4.06 42% 2.86 40% 1.84 37% 1.00 32% 0.35 20% 0.00 0%Area dist sector 6.86 55% 5.37 56% 4.08 58% 2.99 61% 2.09 67% 1.40 79%1.02 100%  Area transition 0.26 2.0%  0.19 2.0%  0.13 1.9%  0.09 1.8% 0.05 1.5%  0.02 0.9%  0.00 0%

Embodiment 2, FIG. 25

Sector Angle Distance 170 Sector Angle Near 160 Sector Angle Transitions30 each recess 15 degrees transition Sector Radius Central 0.57 Pupildiameter 4.00 4.00 3.50 3.50 3.00 3.00 2.50 2.50 2.00 2.00 1.50 1.501.14 1.14 Area Pupil 12.57 9.62 7.07 4.91 3.14 1.77 1.02 Area nearsector 5.13 41% 3.82 40% 2.69 38% 1.73 35% 0.94 30% 0.33 19% 0.00 0%Area dist sector 6.47 52% 5.08 53% 3.88 55% 2.86 58% 2.02 64% 1.37 78%1.02 100%  Area transition 0.96 7.7%  0.72 7.4%  0.50 7.1%  0.32 6.6% 0.18 5.6%  0.06 3.5%  0.00 0%

The IOL was also available without recessed part. This IOL was used asreference lens. It has a dioptre of +20 for the main lens part. The lensof the invention was further identical, except that it had a recessedpart with a relative dioptre of +3 with respect to the main lens part.The measurement procedure above using the PMTF was used. In the table,results using a spatially “large” circular source of 600 mu diameter anda “small” source of 200 mu diameter are shown.

Source Small Large Small Large Small large Pupil 4.5 4.5 3.75 3.75 3.003.00 diameter Light in 54% 58% 54% 54% 54% 54% far focus Light in 40%34% 38% 38% 38% 41% near focus Area  6%  7%  8%  8%  8%  6% transition

The measured results and calculated results thus are comparable.

Embodiment 3, FIG. 26

Sector Angle Distance 182 Sector Angle Near 170 Sector Angle Transitions8 each recess 4 degrees transition Sector Radius Central 0.25 Pupildiameter 4.00 4.00 3.50 3.50 3.00 3.00 2.50 2.50 2.00 2.00 1.50 1.500.50 0.50 Area Pupil 12.57 9.62 7.07 4.91 3.14 1.77 0.20 Area nearsector 5.84 46% 4.45 46% 3.25 46% 2.23 45% 1.39 44% 0.74 42% 0.00 0%Area dist sector 6.45 51% 4.96 52% 3.67 52% 2.58 53% 1.69 54% 0.99 56%0.20 100%  Area transition 0.27 2.2%  0.21 2.2%  0.15 2.2%  0.10 2.1% 0.07 2.1%  0.03 2.0%  0.00 0%

Embodiment 4, FIG. 23

Sector Angle Distance 145 Sector Angle Near 145 Sector Angle Transitions70 each recess 35 degrees transition Sector Radius Central 1 Pupildiameter 4.00 4.00 3.50 3.50 3.00 3.00 2.50 2.50 2.00 2.00 Area Pupil12.57 9.62 7.07 4.91 3.14 Area near sector 3.80 30% 2.61 27% 1.58 22%0.71 15% 0.00  0% Area dist sector 6.94 55% 5.75 60% 4.72 67% 3.85 79%3.14 100%  Area transition 1.83 14.6%  1.26 13.1%  0.76 10.8%  0.347.0%  0.00 0.0%

Embodiment 5, FIG. 22

Sector Angle Distance 145 Sector Angle Near 145 Sector Angle Transitions70 each recess 35 degrees transition Sector Radius Central 0.00 Pupildiameter 4.00 4.00 3.50 3.50 3.00 3.00 2.50 2.50 2.00 2.00 1.50 1.500.00 0.00 Area Pupil 12.57 9.62 7.07 4.91 3.14 1.77 0.00 Area nearsector 5.06 40% 3.88 40% 2.85 40% 1.98 40% 1.27 40% 0.71 40% 0.00 0%Area dist sector 5.06 40% 3.88 40% 2.85 40% 1.98 40% 1.27 40% 0.71 40%0.00 100%  Area transition 2.44 19.4%  1.87 19.4%  1.37 19.4%  0.9519.4%  0.61 19.4%  0.34 19.4%  0.00 0%

For embodiment 2, measurements were made in an Optocraft optical benchaccording to ISO 11979-2. In FIGS. 27-29 measurements are shown ofdevices having a main lens part with an optical power of +22 (FIG. 27),+29 (FIG. 28) and +15 (FIG. 29). The recessed part has a near visionpart having a relative optical power (with respect to the main part) of+3.0. All the examples relate to an IOL with varying optical power ofthe main part. In FIG. 27, the half right below is recessed. In FIG. 28,the recessed part is upper-left, in FIG. 29, the recess is the leftside. The scale is Wave-front/lambda=0.54 micron. In FIG. 27 the totalscale is from −10.6 to 4.6, in FIG. 28 the scale is about −6.8 to 8.8,in FIG. 29 the scale is −12.4 to 6.3. The usual colour scale wasconverted to greyscale.

When manufacturing a MSIOL of the type described in this document byturning, the material removing tool usually moves parallel to therotational axis away from and towards the work piece in a synchronisedway with the angle of rotation. In this way a semi-meridian readingsector 7, 8′, 20 can be created embedded or recessed in the main lenspart 4. When the transition 10 is made from main lens part 4 intorecessed part 7, 8 the tool and the work piece or lens have to be movedtowards each other. When the transition 10 is made out of the recessedpart 7, 8 to the main lens part 4, the tool and the lens have to moveaway from each other. When manufactured this way, a transition zone 10,13, 13′ separates the recessed part(s) from the main lens part 4. Itshould be clear that the dimensions of this transition zone should be assmall as possible. It was found that the best results are provided ifthe transition zones are as small or narrow and thus as steep aspossible.

To make the smallest transition zone the cutting tool and the lensshould be moved towards each other and away from each other as fast aspossible. Often, the tool will move with respect to the lens. Fastdisplacement implies the tool should be moved with the fastestacceleration allowed by the manufacturer of the cutting tool or capableby the cutting tool. The method of the present invention calculates theoptimal transition profile to move the cutting tool from position 1 atrest to position 2 at rest. Position 1 corresponds to the z position ofthe cutting tool when processing the distance part, and position 2corresponds to the position of the cutting tool when processing thereading part or vice versa.

If the movement of the cutting tool is limited by a specified maximumacceleration, then the fastest transition between two positions isaccomplished by performing the displacement of the fast tool with thismaximum acceleration during the whole transition. From simple mechanicsit follows that the displacement s after applying the maximumacceleration a_(max) during a time t₁ is:s=1/2a _(max) t ₁ ²

The cutting tool will now have a speed of:v=a _(max) t ₁

To bring the fast tool back to rest v=0 we apply again the maximumacceleration on the fast tool system but now in the opposite direction.From simple mechanics it follows that the time needed to stop the fasttool t₂ is equal to the time that was needed to accelerate the fasttool.t ₂ =t ₁

When the transition time is Δt half of the transition time is needed toaccelerate the fast tool and half of the transition time is needed tobring the fast tool at rest again. From this the optimised profile thatutilises the maximum allowed acceleration for the tool is given by:

$\begin{matrix}{{s(t)} = {\frac{1}{2}a_{\max}t^{2}}} & {{{For}\mspace{14mu} 0} \leq t < \frac{\Delta\; t}{2}} \\{{s(t)} = {{\frac{1}{2}{a_{\max}\left( \frac{\Delta\; t}{2} \right)}^{2}} + {a_{\max}\frac{\Delta\; t}{2}\left( {t - \frac{\Delta\; t}{2}} \right)} - {\frac{1}{2}{a_{\max}\left( {t - \frac{\Delta\; t}{2}} \right)}^{2}}}} & {{{For}\mspace{14mu}\frac{\Delta\; t}{2}} \leq t \leq {\Delta\; t}}\end{matrix}$

Where Δt is the transition time.

The total and maximum displacement Δs when limited to the maximumacceleration a_(max) of the fast tool is:

${\Delta\; s} = {a_{\max}\left( \frac{\Delta\; t}{2} \right)}^{2}$

The minimum time needed to make a displacement Δs is:

${\Delta\; t} = {2\sqrt{\frac{\Delta\; s}{a_{\max}}}}$

This time is the theoretical minimal time to make a displacement Δs withthe cutting tool that is limited to a maximum acceleration. All othertransition profiles subjected to the same limitation regarding themaximum acceleration require a larger time to make the same displacementΔs.

An important fact is that in practice to achieve a surface manufacturedby turning of good quality the spindle speed is bounded to a minimumnumber of revolutions per minute. If the spindle speed is bounded to aminimum a smaller transition time will result in a smaller transitionzone. The angular size φ in degrees of the transition zone in this casecan be calculated by:

ϕ = N ⋅ 360 ⋅ Δ t$\phi = {{N \cdot 360 \cdot 2}\sqrt{\frac{\Delta\; s}{a_{\max}}}}$with N the spindle speed in revolutions per second.

Generally the height difference between the reading part and distancepart decrease when moving from the periphery toward the centre of theoptical zone. This implies that the angular size of the transition zonecan be made smaller when approaching the centre. In this way theeffective area of the optical zones is maximised. Another importantadvantage is that the transition is made as steep as possible this way.A steep transition can be advantageous, reflections at the transitionzone are in such a way they are less or not perceived as disturbing bythe patient. From this it can be concluded that with the optimisedtransition profile a larger displacement can be achieved for the samesize of the transition profile. Or otherwise when certain amount ofdisplacement is needed to change from distance part to reading part withthe optimised transition profile this can be achieved in a faster wayresulting in a smaller transition zone. A further application for thedescribed optimised transition profile is this. To make a displacementΔs in a time Δt in the most controlled or accurate way it can beadvantageous to make the transition with the minimum acceleration. Theminimum acceleration needed to achieve a displacement Δs in a time Δtcan be calculated with:

$a_{\min =}\frac{4\Delta\; s}{\Delta\; t^{2}}$

The transition profile is given again by:

$\begin{matrix}{{s(t)} = {\frac{1}{2}{at}^{2}}} & {{{For}\mspace{14mu} 0} \leq t < \frac{\Delta\; t}{2}} \\{{s(t)} = {{\frac{1}{2}{a\left( \frac{\Delta\; t}{2} \right)}^{2}} + {a\frac{\Delta\; t}{2}\left( {t - \frac{\Delta\; t}{2}} \right)} - {\frac{1}{2}{a\left( {t - \frac{\Delta\; t}{2}} \right)}^{2}}}} & {{{For}\mspace{14mu}\frac{\Delta\; t}{2}} \leq t \leq {\Delta\; t}}\end{matrix}$

Where Δt is the transition time and a is the maximum acceleration or aspecified acceleration for the most controlled transition. The abovedescribed transition starts with a horizontal slope and ends with ahorizontal slope. For the case that both near and reading part zone arerotational symmetric surfaces both zones have horizontal slopes in thetangential or tool direction. In this case the zones can be connected bythe transition profile in a smooth way with no discontinuity in thefirst derivative. In case one or both zones has or have for example nonrational symmetric surfaces such as a toric surface or a decentredspherical surface, the slope will generally not be horizontal in thetool direction. To make a smooth transition in case one of the zonesdoes not have a horizontal or zero slope in the tangential direction,the transition can be made by removing some part of the beginning or theend of the transition profile in such a way that both zones andtransition zone become tangent at their point of connection. See FIG.17. It's also not difficult to do the same analysis as above in a moregenerally way. That is the assumption that the tool is at rest inposition 1 and in position 2 is dropped. Instead, the tool is allowed tostart with a specified velocity v1 before the transition and remains ata speed v2 after the transition. The last resulting in transitionprofile that does optional not start or end with a horizontal slope. Ofcourse if one chooses it's also possible to start the transition withoutbeing tangent with one or both optical zones.

Example 1

Maximum acceleration for the cutting tool:a _(max)=10 m/sec²

Spindle speed 1200 rev/min (20 rev/sec) with a transition angle of 20degrees.

$\mspace{20mu}{{\Delta\; t} = {{\frac{1}{20}\frac{20}{360}} = {{2.78 \cdot 10^{- 3}}\mspace{14mu}\sec}}}$$\mspace{20mu}{\frac{\Delta\; t}{2} = {{1.39 \cdot 10^{- 3}}\mspace{14mu}\sec}}$  For  0 ≤ t < 1.39 ⋅ 10⁻³:  s(t) = 5t²  For  1.39 ⋅ 10⁻³ ≤ t < 2.78 ⋅ 10⁻³:s(t) = 9.66 ⋅ 10⁻⁶ + 1.39 ⋅ 10⁻³(t − 1.39 ⋅ 10⁻³) − 5(t − 1.39 ⋅ 10⁻³)²

Example 2

Spindle speed N=15 rev/sec. Δs=0.05 mm, a_(max)=10 m/sec²

${\Delta\; t} = {{2\sqrt{\frac{\Delta\; s}{a_{\max}}}} = {0.0045\mspace{14mu}\sec}}$$\phi = {{{N \cdot 360 \cdot 2}\sqrt{\frac{\Delta\; s}{a_{\max}}}} = {{15*360*0.0045} = {24\mspace{14mu}{degrees}}}}$

It's also possible to make the transition by using other less optimalprofiles. For example a transition profile described by the cosinefunction could be used.s(t)=A·cos(ωt)

With A the amplitude and ω the angular frequency. The transition startsat ω=0 and ends at ω=π. The acceleration experienced when following thiscosine profile is:a=−A·ω ² cos(ωt)

The maximum acceleration in the cosine profile will occur at ω=0 and atω=π in the opposite direction. The absolute magnitude of theacceleration is therefore:a _(cos) _(—) _(max) =A·ω ²

Because the maximum acceleration available or allowed for the turningmachine is only used during a very small trajectory in the transitionprofile, the achieved displacement for the fast tool is substantiallyless than the described optimal transition profile in this document.

For comparison purposes, a cosine transition is calculated with the sametransition time and maximum acceleration as used in the example abovewith the optimised transition profile (FIG. 17).

The angular frequency ω can be calculated from the transition time:

$\omega = \frac{\pi}{\Delta\; t}$

The maximum amplitude possible with maximum acceleration a_(max)=10m/sec² is

$A = \frac{a_{\max}}{\left( \frac{\pi}{\Delta\; t} \right)^{2}}$${s(t)} = {A \cdot \left( {1 - {\cos\left( {\frac{\pi}{\Delta\; t}t} \right)}} \right)}$

-   -   Another function that is used to define    -   such a transition is the sigmoid    -   Distance part with radius Rd:        Rd:=10.0        zd(r):=Rd−√{square root over (Rd ² −r ²)}

function as described in WO9716760 and U.S. Pat. No. 6,871,953. Thesigmoid function is defined as (FIG. 18):

${y(t)} = \frac{1}{1 + {\mathbb{e}}^{- t}}$

If y(t) is the displacement as a function of time t, then theacceleration in the sigmoid profile (FIG. 19) is given by:

$a = \frac{\mathbb{d}^{2}{y(t)}}{\mathbb{d}t^{2}}$$a = {\frac{2{\mathbb{e}}^{{- 2}t}}{\left( {{\mathbb{e}}^{- t} + 1} \right)^{3}} - \frac{{\mathbb{e}}^{- t}}{\left( {{\mathbb{e}}^{- t} + 1} \right)^{2}}}$

It shows the acceleration in the profile is not uniform. The maximumacceleration possible is not utilised during the whole transition. Thespeed of the transition is restricted by the extremes in theacceleration profile, see FIG. 19.

The sigmoid function can be scaled and translated to model the requiredtransition. In the same way as shown

with the cosine transition it can be easily shown that a transition thatis described by a sigmoid function is less optimal. That is when limitedto a maximum acceleration during the transition:

-   -   The maximum displacement in a fixed time interval is less

The time needed for a required tool displacement is larger resulting ina wider transition zone.

-   -   Reading part with radius Rr        Rr:=8.5        zr(r):=Rr−√{square root over (Rr ² −r ²)}

Sagitta difference or height difference when moving from reading part todistance part, see FIG. 30:saggdiff(r):=zr(r)−zd(r)

Radial distance s available to take height step when the transition isperformed between two meridians that are a angle α apart at a distance rfrom the optical centre:

$:={2 \cdot \pi \cdot r \cdot \frac{\alpha}{360}}$

Transition profile in the first half part

$z:={\frac{1}{2} \cdot a \cdot x^{2}}$

Should be equal to half the height step

$\frac{{saggdiff}(r)}{2} = {\frac{1}{2} \cdot a \cdot \left( \frac{s(x)}{2} \right)^{2}}$$a:=\frac{{saggdiff}(r)}{\left( \frac{s(x)}{2} \right)^{2}}$$a:=\frac{4 \cdot {{saggdiff}(r)}}{{s(x)}^{2}}$$a:={4 \cdot \frac{\left\lbrack {{Rr} - \sqrt{{Rr}^{2} - r^{2}} - \left( {{Rd} - \sqrt{{Rd}^{2} - r^{2}}} \right\rbrack} \right)}{\left( {2 \cdot \pi \cdot r \cdot \frac{\alpha}{360}} \right)^{2}}}$

Slope half way the transition profile:

$\mspace{79mu}{{slope}:=\left\lbrack {\frac{\mathbb{d}}{\mathbb{d}x}\left( {\frac{1}{2} \cdot a \cdot x} \right)^{2}} \right\rbrack}$     slope := a ⋅ x$\mspace{79mu}{{slope}:={a \cdot \frac{\left( {2 \cdot \pi \cdot r \cdot \frac{\alpha}{360}} \right)}{2}}}$$:={4 \cdot \frac{\left\lbrack {{Rr} - \sqrt{{Rr}^{2} - r^{2}} - \left( {{Rd} - \sqrt{{Rd}^{2} - r^{2}}} \right)} \right\rbrack}{\left( {2 \cdot \pi \cdot r \cdot \frac{\alpha}{360}} \right)^{2}} \cdot \frac{\left( {2 \cdot \pi \cdot r \cdot \frac{\alpha}{360}} \right)}{2}}$$:=\frac{\left\lbrack {{Rr} - \sqrt{{Rr}^{2} - r^{2}} - \left( {{Rd} - \sqrt{{Rd}^{2} - r^{2}}} \right)} \right\rbrack}{\left( {\pi \cdot r \cdot \frac{\alpha}{360}} \right)}$

See FIG. 32, showing a graph of the slope or first derivative of thesteepest part of the blending part as a function of the radial distancefrom the optical centre of the ophthalmic lens, for a blending zonebetween two semi meridian lines enclosing an angle of 15 degrees, andFIG. 31, for a blending part enclosed by two semi meridians enclosing anangle of 4 degrees. Below, several values are shown in a table

Distance slope 15 deg slope 4 deg 0.4 0.027 0.101 0.8 0.054 0.203 1.20.082 0.307 1.6 0.11 0.414 2.0 0.14 0.524 2.4 0.171 0.64 2.8 0.203 0.761

The shape and slope (first derivative) of the blending zone can bemeasured with high accuracy, using for instance a 3D Optical Profiler orForm talysurf, commercial available from Taylor Hobson, the UnitedKingdom. FIG. 35 shows a surface map of a lens according to theinvention.

It was found in clinical trials that with a steep slope and carefulchoice of central part, the contrast of the lens increases. In a recentperformed European multicentric clinical study (Pardubice study data onfile), 25 subjects with 49 eyes, 24 subjects were bilateral implantedwith the inventive MSIOL. These subjects represent a sample selection ofthe population of typical European cataract patients. The contrastsensitivity was measured under photopic conditions with a CSV1000instrument from Vector Vision Inc, Greenville, Ohio, USA U.S. Pat. No.5,078,486. In this study the following Log Mar (Logarithmic Mean AngleResolution) values, measured with the CSV1000, where found for spatialfrequencies 3, 6, 12 and 18 cpd:

spatial frequency (cpd) 3 months StDev 3 1.677 +/− 0.15 6 2.073 +/− 0.1712 1.831 +/− 0.21 18 1.437 +/− 0.19

A contrast sensitivity comparison was made with the two market leadersin MIOL. The AcrySof ReSTOR SN60D3 (Alcon) is a refractive/diffractiveMIOL and the ReZoom (Advanced Medical Optics) is a multizone refractivemultifocal aiming improved visual outcome.

In a recent study titled “Multifocal Apodized Diffractive IOL versusMultifocal Refractive IOL” published in the Journal Cataract RefractSurg 2008; 34:2036-2042 Q 2008 ASCRS and ESCRS, contrast sensitivity wasmeasured in 23 patients who had bilateral implantation of the AcrySofReSTOR SN60D3 IOL and 23 patients who had bilateral implantation of theReZoom IOL. The number of subjects in our study was 24 and thereforedirect comparable with the outcome of this study. It shows a meancontrast sensitivity improvement of at least 25% compared with a stateof the art concentric refractive multifocal lens. The inventive lensconfiguration will give a mean contrast sensitivity for healthy eyes(1.677) at 3 cpd, (2.07) at 6 cpd, (1.831) at 12 cpd and (1.437) at 18cpd. In FIGS. 33 and 34, the results are indicated when compared to theperformance of an average population, for several age groups (Pop. Normhttp://www.vectorvision.com/html/educationCSV1000Norms.html), theperformance of the test group before surgery (pre-op), and theperformance with an MIOL indicated as LS 312-MF. These results werefound consistent at 6 months post operative, i.e., 6 months aftersurgery.

It will also be clear that the above description and drawings areincluded to illustrate some embodiments of the invention, and not tolimit the scope of protection. Starting from this disclosure, many moreembodiments will be evident to a skilled person which are within thescope of protection and the essence of this invention and which areobvious combinations of prior art techniques and the disclosure of thispatent.

The invention claimed is:
 1. An ophthalmic lens comprising a main lenspart having a surface, a recessed part having a surface which isrecessed with respect to said surface of said main lens part, an opticalcentre, and an optical axis through said optical centre, said main lenspart having at least one boundary with said recessed part, said mainlens part having an optical power of between about −20 to about +35dioptre, said recessed part positioned at a distance of less than 2 mmfrom said optical centre and comprising a near part having a relativedioptre of about +1.0 to about +5.0 with respect to the optical power ofsaid main lens part, said at least one boundary of said main lens partwith said recessed lens part form a blending part or blending parts,which said blending parts are shaped to refract light away from saidoptical axis and have a curvature resulting in a loss of light, within acircle with a diameter of 4 mm around said optical centre, of less thanabout 15%, said loss of light defined as the fraction of the amount ofin-focus light from the ophthalmic lens compared to the amount ofin-focus light from an identical ophthalmic lens without said recessedpart, wherein said recessed part is at two sides bounded by blendingparts running through said optical centre, the recessed part thus beingshaped as a meridian zone, said blending parts at said two sides beingwithin semi-meridians enclosing an angle larger than 1 degree and lessthan 17 degrees, a shape of said blending parts having an S-shaped curvehaving a steepest part with a slope or first derivative that isdependent on a radial distance from the optical centre, the slope at aradial distance of 1.6 mm from the optical centre having a steepness ofmore than 0.1.
 2. The ophthalmic lens according to claim 1, wherein saidcurvature results in a loss of light, within a circle with a diameter of4 mm around said optical centre, of between about 2% to about 15%. 3.The ophthalmic lens according to claim 1, the main lens part having anoptical power of between about −10 to about +30 dioptre.
 4. Theophthalmic lens according to claim 1, wherein said recessed part ispositioned at a distance of less than 1.5 mm from said optical centre.5. The ophthalmic lens according to claim 1, wherein said near part hasa relative dioptre of about +1.50 to about +4.00 dioptre with respect tothe optical power of said main lens part.
 6. The ophthalmic lensaccording to claim 1, wherein said boundaries of said recessed lens partwith said main lens part have a curvature resulting in a loss of light,within a circle with a diameter of 4 mm around said optical centre, ofbelow about 10%.
 7. The ophthalmic lens according to claim 1, whereinsaid main lens part has a curvature with a curvature radius Rv, and theouter limit of the recess lies on or within the curvature radius Rv. 8.The ophthalmic lens according to claim 1, further comprising a centralpart which has a relative optical power of about −2.0 to +2.0 dioptrewith respect to said main lens part.
 9. The ophthalmic lens according toclaim 8, wherein the size of said central part is such that it fitswithin a circumscribing circle with a diameter of about 0.2-3.0 mm. 10.The ophthalmic lens according to claim 8, wherein the size of saidcentral part is such that it fits within a circumscribing circle with adiameter of about 0.2-2.0 mm.
 11. The ophthalmic lens according to claim8, wherein said central part is circular.
 12. The ophthalmic lensaccording to claim 8, wherein said recessed part is at at least oneboundary bounded by said central part.
 13. The ophthalmic lens accordingto claim 8, wherein said central part has a cross section of about0.60-1.20 mm.
 14. The ophthalmic lens according to claim 1 andcomprising said recessed part shaped as a meridian zone, wherein saidrecessed part has an included angle of about 160-200 degrees.
 15. Theophthalmic lens according to claim 14, wherein said recessed part has anincluded angle of about 175-195 degrees.
 16. The ophthalmic lensaccording to claim 1, having a cross section diameter of about 5.5-7 mm.17. The ophthalmic lens according to claim 1, wherein the main lens partis in the form of a distance lens.
 18. The ophthalmic lens according toclaim 1, wherein the recessed part forms a reading part.
 19. Theophthalmic lens according to claim 8, wherein said recessed part isbounded by two semi meridians and a line of latitude concentric and at adistance from said central part.
 20. The ophthalmic lens according toclaim 1, wherein said recessed part comprises at least two sub-zonehaving optical powers which differ.
 21. The ophthalmic lens according toclaim 20, wherein said sub-zones are concentric.
 22. The ophthalmic lensaccording to claim 21, wherein optical powers of said sub-zones increasein radial direction.
 23. The ophthalmic lens according to claim 1,wherein the optical power of said recessed part increases in radialdirection.
 24. The ophthalmic lens according to claim 1, wherein saidrecessed part comprises a diffractive optics part.
 25. The ophthalmiclens according to claim 1, wherein said recessed part comprises a first,central subzone and two further subzones circumferentially neighbouringat both sides of said first subzone.
 26. The ophthalmic lens accordingto claim 25, wherein said first subzone has an optical power larger thanthe optical power of the further subzones.
 27. The ophthalmic lensaccording to claim 25, wherein said two further subzones have an opticalpower larger than the optical power of said main lens part.
 28. Theophthalmic lens according to claim 1, wherein at least one of saidblending parts, has an S-shaped curve which follows a first paraboliccurve running from the main lens part surface towards the surface of therecessed part, having an intermediate curve part connecting to saidfirst parabolic curve, and continuing with following a second paraboliccurve ending at the recessed surface.
 29. An add on intraocular lens(IOL) to be inserted in the bag, the sulcus, as cornea inlay or ananterior chamber lens, comprising the ophthalmic lens according to claim1, wherein said main lens part has an optical power of about −10 to +5dioptre.
 30. An oculary supported multifocal corrective lens providedwith a circular central lens portion, a lower lens portion in a lowerlens part neighbouring said central lens portion, and a further lensportion, the lower lens portion comprises a recess comprising two sideswhich run from said central lens portion towards the rim of the lens,the outer limit of the lower lens portion lies on or within an imaginarysphere having its origin and radius of curvature coinciding with theradius Rv of said further lens portion, wherein said two sides providesloping from the further lens portion surface to the recessed surface ofthe lower lens portion, said sloping at least partly following a firstparabolic curve running from the further lens portion surface towardsthe lower lens portion surface, and continuing with following at leastpartly a second parabolic curve ending at the recessed surface.
 31. Anophthalmic lens comprising a main lens part, a recessed part, an opticalcentre, and an optical axis through said optical centre, said main lenspart having at least one boundary with said recessed part, said recessedpart positioned at a distance from said optical centre, boundaries ofsaid recessed lens part with said main lens part are formed as blendingparts which are shaped to refract light away from said optical axis,said main lens part, central part, recessed part and blending partsmutually positioned and shaped for providing a Log CS characteristicunder photopic light conditions within 6 months post-operative in aspacial frequency (cpd) between 3-18 which is at least between thepopulation norm of 11-19 years and 50-75 years.
 32. The ophthalmic lensof claim 31, wherein in a spacial frequency (cpd) between about 6 and18, its Log CS characteristic under photopic light conditions within 6months post operative is above the population norm of 20-55 years. 33.An intra ocular lens (IOL) comprising a lens with a main lens parthaving a surface, a recessed part having a surface which is recessedwith respect to said surface of said main lens part, an optical centre,and an optical axis through said optical centre, said main lens parthaving at least one boundary with said recessed part, said main lenspart having an optical power of between about −20 to about +35 dioptre,said recessed part positioned at a distance of less than 2 mm from saidoptical centre and comprising a near part having a relative dioptre ofabout +1.0 to about +5.0 with respect to the optical power of said mainlens part, said at least one boundary of said main lens part with saidrecessed lens part form a blending part or blending parts shaped torefract light away from said optical axis, wherein said recessed part isat two sides bounded by blending parts running through said opticalcentre, the recessed part thus being shaped as a meridian zone, saidblending parts at said two sides being within semi-meridians enclosingan angle larger than 1 degree and less than 17 degrees, a shape of saidblending parts having an S-shaped curve having a steepest part with aslope or first derivative that is dependent on a radial distance fromthe optical centre, the slope at a radial distance of 1.6 mm from theoptical centre having a steepness of more than 0.1.
 34. The ophthalmiclens according to claim 33, wherein, further comprising a central partwhich has a relative optical power of about −2.0 to +2.0 dioptre withrespect to said main lens part, wherein said central part fits within acircumscribing circle with a diameter of about 0.2-2.0 mm.
 35. The IOLaccording to claim 33, wherein said blending part or blending parts havea curvature resulting in a loss of light, within a circle with adiameter of 4 mm around said optical centre, of less than about 15%,said loss of light defined as the fraction of the amount of in-focuslight from the IOL compared to the amount of in-focus light from anidentical IOL without said recessed part.
 36. The IOL according to claim35, wherein said loss of light is below about 10%.
 37. The IOL accordingto claim 33, wherein said recessed part is at two sides bounded bysemi-meridians running from said optical centre, the recessed part thusshape as a meridian zone.
 38. The IOL of claim 37, wherein said recessedpart has an included angle of about 175-195 degrees.
 39. The IOLaccording to claim 34 wherein said recessed part is bounded by two semimeridians and a line of latitude concentric and at a distance from saidcentral part.
 40. The IOL according to claim 33, wherein two blendingparts are each within semi meridians which enclose an angle (γ) of lessthan 15 degrees.
 41. The IOL according to claim 33, wherein the slope ofsaid blending parts have an S-shaped curve and have a steepness with aslope or first derivative at a central range of the blending part at 1.6mm from said optical centre of more than 0.1 at the steepest part. 42.The IOL according to claim 33, wherein said blending parts have anS-shaped curve and have a steepness with a slope or first derivative ata central range of the blending part at 2.8 mm from said optical centreof more than 0.2 at the steepest part.
 43. The IOL according to claim33, wherein at least one of said blending parts, has or have an S-shapedcurve, which follows or follow a first parabolic curve running from themain lens part surface towards the surface of the recessed part, havingan intermediate curve part connecting to said first parabolic curve, andcontinuing with following a second parabolic curve ending at therecessed surface.
 44. The IOL of claim 43, wherein said intermediatecurve part at the steepest part has a first derivative of at least 0.05at 0.4 mm from said optical centre.
 45. The IOL according to claim 34,said main lens part, central part, recessed part and blending partsmutually positioned and shaped for providing a Log CS characteristicunder photopic light conditions within 6 months post-operative in aspacial frequency (cpd) between 3-18 which is at least between thepopulation norm of 11-19 years and 50-75 years.
 46. An add-on IOL to beinserted in the bag, the sulcus, as cornea inlay or an anterior chamberlens, comprising the IOL according to claim 33, wherein said main lenspart has an optical power of about −10 to +5 dioptre.
 47. A method forproviding a subject with the intraocular lens (IOL) according to claim34, said method comprises the steps of determining the pupil diameter ofsaid subject, and producing the IOL with the diameter of said centralpart adapted to the pupil diameter of the subject.
 48. The ophthalmiclens according to claim 1, wherein the slope or first derivativeincreases with the radial distance from the optical centre.
 49. Theophthalmic lens according to claim 1, wherein the slope or firstderivative is linearly dependent on the radial distance from the opticalcentre.
 50. The ophthalmic lens according to claim 1, wherein theoptical power of said recessed part decreases in radial direction. 51.The ophthalmic lens according to claim 33, wherein the slope or firstderivative increases with the radial distance from the optical centre.52. The ophthalmic lens according to claim 33, wherein the slope orfirst derivative is linearly dependent on the radial distance from theoptical centre.
 53. The ophthalmic lens according to claim 33, whereinthe optical power of said recessed part decreases in radial direction.